Add SMI driver

raspberrypi inclusion
category: feature
bugzilla: 50432

--------------------------------
Signed-off-by: NLuke Wren <wren6991@gmail.com>

MISC: bcm2835: smi: use clock manager and fix reload issues

Use clock manager instead of self-made clockmanager.

Also fix some error paths that showd up during development
(especially missing release of dma resources on rmmod)
Signed-off-by: NMartin Sperl <kernel@martin.sperl.org>

bcm2835_smi: re-add dereference to fix DMA transfers
Signed-off-by: NFang Yafen <yafen@iscas.ac.cn>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

Documentation/devicetree/bindings/misc/brcm,bcm2835-smi-dev.txt

+* Broadcom BCM2835 SMI character device driver.
+
+SMI or secondary memory interface is a peripheral specific to certain Broadcom
+SOCs, and is helpful for talking to things like parallel-interface displays
+and NAND flashes (in fact, most things with a parallel register interface).
+
+This driver adds a character device which provides a user-space interface to
+an instance of the SMI driver.
+
+Required properties:
+- compatible: "brcm,bcm2835-smi-dev"
+- smi_handle: a phandle to the smi node.
+
+Optional properties:
+- None.
+
+

Documentation/devicetree/bindings/misc/brcm,bcm2835-smi.txt

+* Broadcom BCM2835 SMI driver.
+
+SMI or secondary memory interface is a peripheral specific to certain Broadcom
+SOCs, and is helpful for talking to things like parallel-interface displays
+and NAND flashes (in fact, most things with a parallel register interface).
+
+Required properties:
+- compatible: "brcm,bcm2835-smi"
+- reg: Should contain location and length of SMI registers and SMI clkman regs
+- interrupts: *the* SMI interrupt.
+- pinctrl-names: should be "default".
+- pinctrl-0: the phandle of the gpio pin node.
+- brcm,smi-clock-source: the clock source for clkman
+- brcm,smi-clock-divisor: the integer clock divisor for clkman
+- dmas: the dma controller phandle and the DREQ number (4 on a 2835)
+- dma-names: the name used by the driver to request its channel.
+  Should be "rx-tx".
+
+Optional properties:
+- None.
+
+Examples:
+
+8 data pin configuration:
+
+smi: smi@7e600000 {
+	compatible = "brcm,bcm2835-smi";
+	reg = <0x7e600000 0x44>, <0x7e1010b0 0x8>;
+	interrupts = <2 16>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&smi_pins>;
+	brcm,smi-clock-source = <6>;
+	brcm,smi-clock-divisor = <4>;
+	dmas = <&dma 4>;
+	dma-names = "rx-tx";
+
+	status = "okay";
+};
+
+smi_pins: smi_pins {
+	brcm,pins = <2 3 4 5 6 7 8 9 10 11 12 13 14 15>;
+	/* Alt 1: SMI */
+	brcm,function = <5 5 5 5 5 5 5 5 5 5 5 5 5 5>;
+	/* /CS, /WE and /OE are pulled high, as they are
+	   generally active low signals */
+	brcm,pull = <2 2 2 2 2 2 0 0 0 0 0 0 0 0>;
+};
+

drivers/char/broadcom/Kconfig

@@ -24,3 +24,12 @@ config BCM2835_DEVGPIOMEM
 		Provides users with root-free access to the GPIO registers
 		on the 2835. Calling mmap(/dev/gpiomem) will map the GPIO
 		register page to the user's pointer.
+
+config BCM2835_SMI_DEV
+	tristate "Character device driver for BCM2835 Secondary Memory Interface"
+	depends on BCM2835_SMI
+	default m
+	help
+		This driver provides a character device interface (ioctl + read/write) to
+		Broadcom's Secondary Memory interface. The low-level functionality is provided
+		by the SMI driver itself.

drivers/char/broadcom/Makefile

 obj-$(CONFIG_BCM2708_VCMEM)	+= vc_mem.o
 obj-$(CONFIG_BCM2835_DEVGPIOMEM)+= bcm2835-gpiomem.o
+obj-$(CONFIG_BCM2835_SMI_DEV)	+= bcm2835_smi_dev.o

drivers/char/broadcom/bcm2835_smi_dev.c

+/**
+ * Character device driver for Broadcom Secondary Memory Interface
+ *
+ * Written by Luke Wren <luke@raspberrypi.org>
+ * Copyright (c) 2015, Raspberry Pi (Trading) Ltd.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the above-listed copyright holders may not be used
+ *    to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * ALTERNATIVELY, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2, as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/fs.h>
+
+#include <linux/broadcom/bcm2835_smi.h>
+
+#define DEVICE_NAME "bcm2835-smi-dev"
+#define DRIVER_NAME "smi-dev-bcm2835"
+#define DEVICE_MINOR 0
+
+static struct cdev bcm2835_smi_cdev;
+static dev_t bcm2835_smi_devid;
+static struct class *bcm2835_smi_class;
+static struct device *bcm2835_smi_dev;
+
+struct bcm2835_smi_dev_instance {
+	struct device *dev;
+};
+
+static struct bcm2835_smi_instance *smi_inst;
+static struct bcm2835_smi_dev_instance *inst;
+
+static const char *const ioctl_names[] = {
+	"READ_SETTINGS",
+	"WRITE_SETTINGS",
+	"ADDRESS"
+};
+
+/****************************************************************************
+*
+*   SMI chardev file ops
+*
+***************************************************************************/
+static long
+bcm2835_smi_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	long ret = 0;
+
+	dev_info(inst->dev, "serving ioctl...");
+
+	switch (cmd) {
+	case BCM2835_SMI_IOC_GET_SETTINGS:{
+		struct smi_settings *settings;
+
+		dev_info(inst->dev, "Reading SMI settings to user.");
+		settings = bcm2835_smi_get_settings_from_regs(smi_inst);
+		if (copy_to_user((void *)arg, settings,
+				 sizeof(struct smi_settings)))
+			dev_err(inst->dev, "settings copy failed.");
+		break;
+	}
+	case BCM2835_SMI_IOC_WRITE_SETTINGS:{
+		struct smi_settings *settings;
+
+		dev_info(inst->dev, "Setting user's SMI settings.");
+		settings = bcm2835_smi_get_settings_from_regs(smi_inst);
+		if (copy_from_user(settings, (void *)arg,
+				   sizeof(struct smi_settings)))
+			dev_err(inst->dev, "settings copy failed.");
+		else
+			bcm2835_smi_set_regs_from_settings(smi_inst);
+		break;
+	}
+	case BCM2835_SMI_IOC_ADDRESS:
+		dev_info(inst->dev, "SMI address set: 0x%02x", (int)arg);
+		bcm2835_smi_set_address(smi_inst, arg);
+		break;
+	default:
+		dev_err(inst->dev, "invalid ioctl cmd: %d", cmd);
+		ret = -ENOTTY;
+		break;
+	}
+
+	return ret;
+}
+
+static int bcm2835_smi_open(struct inode *inode, struct file *file)
+{
+	int dev = iminor(inode);
+
+	dev_dbg(inst->dev, "SMI device opened.");
+
+	if (dev != DEVICE_MINOR) {
+		dev_err(inst->dev,
+			"bcm2835_smi_release: Unknown minor device: %d",
+			dev);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static int bcm2835_smi_release(struct inode *inode, struct file *file)
+{
+	int dev = iminor(inode);
+
+	if (dev != DEVICE_MINOR) {
+		dev_err(inst->dev,
+			"bcm2835_smi_release: Unknown minor device %d", dev);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static ssize_t dma_bounce_user(
+	enum dma_transfer_direction dma_dir,
+	char __user *user_ptr,
+	size_t count,
+	struct bcm2835_smi_bounce_info *bounce)
+{
+	int chunk_size;
+	int chunk_no = 0;
+	int count_left = count;
+
+	while (count_left) {
+		int rv;
+		void *buf;
+
+		/* Wait for current chunk to complete: */
+		if (down_timeout(&bounce->callback_sem,
+			msecs_to_jiffies(1000))) {
+			dev_err(inst->dev, "DMA bounce timed out");
+			count -= (count_left);
+			break;
+		}
+
+		if (bounce->callback_sem.count >= DMA_BOUNCE_BUFFER_COUNT - 1)
+			dev_err(inst->dev, "WARNING: Ring buffer overflow");
+		chunk_size = count_left > DMA_BOUNCE_BUFFER_SIZE ?
+			DMA_BOUNCE_BUFFER_SIZE : count_left;
+		buf = bounce->buffer[chunk_no % DMA_BOUNCE_BUFFER_COUNT];
+		if (dma_dir == DMA_DEV_TO_MEM)
+			rv = copy_to_user(user_ptr, buf, chunk_size);
+		else
+			rv = copy_from_user(buf, user_ptr, chunk_size);
+		if (rv)
+			dev_err(inst->dev, "copy_*_user() failed!: %d", rv);
+		user_ptr += chunk_size;
+		count_left -= chunk_size;
+		chunk_no++;
+	}
+	return count;
+}
+
+static ssize_t
+bcm2835_read_file(struct file *f, char __user *user_ptr,
+		  size_t count, loff_t *offs)
+{
+	int odd_bytes;
+
+	dev_dbg(inst->dev, "User reading %zu bytes from SMI.", count);
+	/* We don't want to DMA a number of bytes % 4 != 0 (32 bit FIFO) */
+	if (count > DMA_THRESHOLD_BYTES)
+		odd_bytes = count & 0x3;
+	else
+		odd_bytes = count;
+	count -= odd_bytes;
+	if (count) {
+		struct bcm2835_smi_bounce_info *bounce;
+
+		count = bcm2835_smi_user_dma(smi_inst,
+			DMA_DEV_TO_MEM, user_ptr, count,
+			&bounce);
+		if (count)
+			count = dma_bounce_user(DMA_DEV_TO_MEM, user_ptr,
+				count, bounce);
+	}
+	if (odd_bytes) {
+		/* Read from FIFO directly if not using DMA */
+		uint8_t buf[DMA_THRESHOLD_BYTES];
+
+		bcm2835_smi_read_buf(smi_inst, buf, odd_bytes);
+		if (copy_to_user(user_ptr, buf, odd_bytes))
+			dev_err(inst->dev, "copy_to_user() failed.");
+		count += odd_bytes;
+
+	}
+	return count;
+}
+
+static ssize_t
+bcm2835_write_file(struct file *f, const char __user *user_ptr,
+		   size_t count, loff_t *offs)
+{
+	int odd_bytes;
+
+	dev_dbg(inst->dev, "User writing %zu bytes to SMI.", count);
+	if (count > DMA_THRESHOLD_BYTES)
+		odd_bytes = count & 0x3;
+	else
+		odd_bytes = count;
+	count -= odd_bytes;
+	if (count) {
+		struct bcm2835_smi_bounce_info *bounce;
+
+		count = bcm2835_smi_user_dma(smi_inst,
+			DMA_MEM_TO_DEV, (char __user *)user_ptr, count,
+			&bounce);
+		if (count)
+			count = dma_bounce_user(DMA_MEM_TO_DEV,
+				(char __user *)user_ptr,
+				count, bounce);
+	}
+	if (odd_bytes) {
+		uint8_t buf[DMA_THRESHOLD_BYTES];
+
+		if (copy_from_user(buf, user_ptr, odd_bytes))
+			dev_err(inst->dev, "copy_from_user() failed.");
+		else
+			bcm2835_smi_write_buf(smi_inst, buf, odd_bytes);
+		count += odd_bytes;
+	}
+	return count;
+}
+
+static const struct file_operations
+bcm2835_smi_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = bcm2835_smi_ioctl,
+	.open = bcm2835_smi_open,
+	.release = bcm2835_smi_release,
+	.read = bcm2835_read_file,
+	.write = bcm2835_write_file,
+};
+
+
+/****************************************************************************
+*
+*   bcm2835_smi_probe - called when the driver is loaded.
+*
+***************************************************************************/
+
+static int bcm2835_smi_dev_probe(struct platform_device *pdev)
+{
+	int err;
+	void *ptr_err;
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node, *smi_node;
+
+	if (!node) {
+		dev_err(dev, "No device tree node supplied!");
+		return -EINVAL;
+	}
+
+	smi_node = of_parse_phandle(node, "smi_handle", 0);
+
+	if (!smi_node) {
+		dev_err(dev, "No such property: smi_handle");
+		return -ENXIO;
+	}
+
+	smi_inst = bcm2835_smi_get(smi_node);
+
+	if (!smi_inst)
+		return -EPROBE_DEFER;
+
+	/* Allocate buffers and instance data */
+
+	inst = devm_kzalloc(dev, sizeof(*inst), GFP_KERNEL);
+
+	if (!inst)
+		return -ENOMEM;
+
+	inst->dev = dev;
+
+	/* Create character device entries */
+
+	err = alloc_chrdev_region(&bcm2835_smi_devid,
+				  DEVICE_MINOR, 1, DEVICE_NAME);
+	if (err != 0) {
+		dev_err(inst->dev, "unable to allocate device number");
+		return -ENOMEM;
+	}
+	cdev_init(&bcm2835_smi_cdev, &bcm2835_smi_fops);
+	bcm2835_smi_cdev.owner = THIS_MODULE;
+	err = cdev_add(&bcm2835_smi_cdev, bcm2835_smi_devid, 1);
+	if (err != 0) {
+		dev_err(inst->dev, "unable to register device");
+		err = -ENOMEM;
+		goto failed_cdev_add;
+	}
+
+	/* Create sysfs entries */
+
+	bcm2835_smi_class = class_create(THIS_MODULE, DEVICE_NAME);
+	ptr_err = bcm2835_smi_class;
+	if (IS_ERR(ptr_err))
+		goto failed_class_create;
+
+	bcm2835_smi_dev = device_create(bcm2835_smi_class, NULL,
+					bcm2835_smi_devid, NULL,
+					"smi");
+	ptr_err = bcm2835_smi_dev;
+	if (IS_ERR(ptr_err))
+		goto failed_device_create;
+
+	dev_info(inst->dev, "initialised");
+
+	return 0;
+
+failed_device_create:
+	class_destroy(bcm2835_smi_class);
+failed_class_create:
+	cdev_del(&bcm2835_smi_cdev);
+	err = PTR_ERR(ptr_err);
+failed_cdev_add:
+	unregister_chrdev_region(bcm2835_smi_devid, 1);
+	dev_err(dev, "could not load bcm2835_smi_dev");
+	return err;
+}
+
+/****************************************************************************
+*
+*   bcm2835_smi_remove - called when the driver is unloaded.
+*
+***************************************************************************/
+
+static int bcm2835_smi_dev_remove(struct platform_device *pdev)
+{
+	device_destroy(bcm2835_smi_class, bcm2835_smi_devid);
+	class_destroy(bcm2835_smi_class);
+	cdev_del(&bcm2835_smi_cdev);
+	unregister_chrdev_region(bcm2835_smi_devid, 1);
+
+	dev_info(inst->dev, "SMI character dev removed - OK");
+	return 0;
+}
+
+/****************************************************************************
+*
+*   Register the driver with device tree
+*
+***************************************************************************/
+
+static const struct of_device_id bcm2835_smi_dev_of_match[] = {
+	{.compatible = "brcm,bcm2835-smi-dev",},
+	{ /* sentinel */ },
+};
+
+MODULE_DEVICE_TABLE(of, bcm2835_smi_dev_of_match);
+
+static struct platform_driver bcm2835_smi_dev_driver = {
+	.probe = bcm2835_smi_dev_probe,
+	.remove = bcm2835_smi_dev_remove,
+	.driver = {
+		   .name = DRIVER_NAME,
+		   .owner = THIS_MODULE,
+		   .of_match_table = bcm2835_smi_dev_of_match,
+		   },
+};
+
+module_platform_driver(bcm2835_smi_dev_driver);
+
+MODULE_ALIAS("platform:smi-dev-bcm2835");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION(
+	"Character device driver for BCM2835's secondary memory interface");
+MODULE_AUTHOR("Luke Wren <luke@raspberrypi.org>");

drivers/misc/Kconfig

@@ -9,6 +9,14 @@ config SENSORS_LIS3LV02D
 	tristate
 	depends on INPUT
 
+config BCM2835_SMI
+	tristate "Broadcom 283x Secondary Memory Interface driver"
+	depends on ARCH_BCM2835
+	default m
+	help
+		Driver for enabling and using Broadcom's Secondary/Slow Memory Interface.
+		Appears as /dev/bcm2835_smi. For ioctl interface see drivers/misc/bcm2835_smi.h
+
 config AD525X_DPOT
 	tristate "Analog Devices Digital Potentiometers"
 	depends on (I2C || SPI) && SYSFS

drivers/misc/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_AD525X_DPOT_SPI)	+= ad525x_dpot-spi.o
 obj-$(CONFIG_INTEL_MID_PTI)	+= pti.o
 obj-$(CONFIG_ATMEL_SSC)		+= atmel-ssc.o
 obj-$(CONFIG_ATMEL_TCLIB)	+= atmel_tclib.o
+obj-$(CONFIG_BCM2835_SMI)	+= bcm2835_smi.o
 obj-$(CONFIG_DUMMY_IRQ)		+= dummy-irq.o
 obj-$(CONFIG_ICS932S401)	+= ics932s401.o
 obj-$(CONFIG_LKDTM)		+= lkdtm/

include/linux/broadcom/bcm2835_smi.h

+/**
+ * Declarations and definitions for Broadcom's Secondary Memory Interface
+ *
+ * Written by Luke Wren <luke@raspberrypi.org>
+ * Copyright (c) 2015, Raspberry Pi (Trading) Ltd.
+ * Copyright (c) 2010-2012 Broadcom. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the above-listed copyright holders may not be used
+ *    to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * ALTERNATIVELY, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2, as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef BCM2835_SMI_H
+#define BCM2835_SMI_H
+
+#include <linux/ioctl.h>
+
+#ifndef __KERNEL__
+#include <stdint.h>
+#include <stdbool.h>
+#endif
+
+#define BCM2835_SMI_IOC_MAGIC 0x1
+#define BCM2835_SMI_INVALID_HANDLE (~0)
+
+/* IOCTLs 0x100...0x1ff are not device-specific - we can use them */
+#define BCM2835_SMI_IOC_GET_SETTINGS    _IO(BCM2835_SMI_IOC_MAGIC, 0)
+#define BCM2835_SMI_IOC_WRITE_SETTINGS  _IO(BCM2835_SMI_IOC_MAGIC, 1)
+#define BCM2835_SMI_IOC_ADDRESS	 _IO(BCM2835_SMI_IOC_MAGIC, 2)
+#define BCM2835_SMI_IOC_MAX	     2
+
+#define SMI_WIDTH_8BIT 0
+#define SMI_WIDTH_16BIT 1
+#define SMI_WIDTH_9BIT 2
+#define SMI_WIDTH_18BIT 3
+
+/* max number of bytes where DMA will not be used */
+#define DMA_THRESHOLD_BYTES 128
+#define DMA_BOUNCE_BUFFER_SIZE (1024 * 1024 / 2)
+#define DMA_BOUNCE_BUFFER_COUNT 3
+
+
+struct smi_settings {
+	int data_width;
+	/* Whether or not to pack multiple SMI transfers into a
+	   single 32 bit FIFO word */
+	bool pack_data;
+
+	/* Timing for reads (writes the same but for WE)
+	 *
+	 * OE ----------+	   +--------------------
+	 *		|	   |
+	 *		+----------+
+	 * SD -<==============================>-----------
+	 * SA -<=========================================>-
+	 *    <-setup->  <-strobe ->  <-hold ->  <- pace ->
+	 */
+
+	int read_setup_time;
+	int read_hold_time;
+	int read_pace_time;
+	int read_strobe_time;
+
+	int write_setup_time;
+	int write_hold_time;
+	int write_pace_time;
+	int write_strobe_time;
+
+	bool dma_enable;		/* DREQs */
+	bool dma_passthrough_enable;	/* External DREQs */
+	int dma_read_thresh;
+	int dma_write_thresh;
+	int dma_panic_read_thresh;
+	int dma_panic_write_thresh;
+};
+
+/****************************************************************************
+*
+*   Declare exported SMI functions
+*
+***************************************************************************/
+
+#ifdef __KERNEL__
+
+#include <linux/dmaengine.h> /* for enum dma_transfer_direction */
+#include <linux/of.h>
+#include <linux/semaphore.h>
+
+struct bcm2835_smi_instance;
+
+struct bcm2835_smi_bounce_info {
+	struct semaphore callback_sem;
+	void *buffer[DMA_BOUNCE_BUFFER_COUNT];
+	dma_addr_t phys[DMA_BOUNCE_BUFFER_COUNT];
+	struct scatterlist sgl[DMA_BOUNCE_BUFFER_COUNT];
+};
+
+
+void bcm2835_smi_set_regs_from_settings(struct bcm2835_smi_instance *);
+
+struct smi_settings *bcm2835_smi_get_settings_from_regs(
+	struct bcm2835_smi_instance *inst);
+
+void bcm2835_smi_write_buf(
+	struct bcm2835_smi_instance *inst,
+	const void *buf,
+	size_t n_bytes);
+
+void bcm2835_smi_read_buf(
+	struct bcm2835_smi_instance *inst,
+	void *buf,
+	size_t n_bytes);
+
+void bcm2835_smi_set_address(struct bcm2835_smi_instance *inst,
+	unsigned int address);
+
+ssize_t bcm2835_smi_user_dma(
+	struct bcm2835_smi_instance *inst,
+	enum dma_transfer_direction dma_dir,
+	char __user *user_ptr,
+	size_t count,
+	struct bcm2835_smi_bounce_info **bounce);
+
+struct bcm2835_smi_instance *bcm2835_smi_get(struct device_node *node);
+
+#endif /* __KERNEL__ */
+
+/****************************************************************
+*
+*	Implementation-only declarations
+*
+****************************************************************/
+
+#ifdef BCM2835_SMI_IMPLEMENTATION
+
+/* Clock manager registers for SMI clock: */
+#define CM_SMI_BASE_ADDRESS ((BCM2708_PERI_BASE) + 0x1010b0)
+/* Clock manager "password" to protect registers from spurious writes */
+#define CM_PWD (0x5a << 24)
+
+#define CM_SMI_CTL	0x00
+#define CM_SMI_DIV	0x04
+
+#define CM_SMI_CTL_FLIP (1 << 8)
+#define CM_SMI_CTL_BUSY (1 << 7)
+#define CM_SMI_CTL_KILL (1 << 5)
+#define CM_SMI_CTL_ENAB (1 << 4)
+#define CM_SMI_CTL_SRC_MASK (0xf)
+#define CM_SMI_CTL_SRC_OFFS (0)
+
+#define CM_SMI_DIV_DIVI_MASK (0xf <<  12)
+#define CM_SMI_DIV_DIVI_OFFS (12)
+#define CM_SMI_DIV_DIVF_MASK (0xff << 4)
+#define CM_SMI_DIV_DIVF_OFFS (4)
+
+/* SMI register mapping:*/
+#define SMI_BASE_ADDRESS ((BCM2708_PERI_BASE) + 0x600000)
+
+#define SMICS	0x00	/* control + status register		*/
+#define SMIL	0x04	/* length/count (n external txfers)	*/
+#define SMIA	0x08	/* address register			*/
+#define SMID	0x0c	/* data register			*/
+#define SMIDSR0	0x10	/* device 0 read settings		*/
+#define SMIDSW0	0x14	/* device 0 write settings		*/
+#define SMIDSR1	0x18	/* device 1 read settings		*/
+#define SMIDSW1	0x1c	/* device 1 write settings		*/
+#define SMIDSR2	0x20	/* device 2 read settings		*/
+#define SMIDSW2	0x24	/* device 2 write settings		*/
+#define SMIDSR3	0x28	/* device 3 read settings		*/
+#define SMIDSW3	0x2c	/* device 3 write settings		*/
+#define SMIDC	0x30	/* DMA control registers		*/
+#define SMIDCS	0x34	/* direct control/status register	*/
+#define SMIDA	0x38	/* direct address register		*/
+#define SMIDD	0x3c	/* direct data registers		*/
+#define SMIFD	0x40	/* FIFO debug register			*/
+
+
+
+/* Control and Status register bits:
+ * SMICS_RXF	: RX fifo full: 1 when RX fifo is full
+ * SMICS_TXE	: TX fifo empty: 1 when empty.
+ * SMICS_RXD	: RX fifo contains data: 1 when there is data.
+ * SMICS_TXD	: TX fifo can accept data: 1 when true.
+ * SMICS_RXR	: RX fifo needs reading: 1 when fifo more than 3/4 full, or
+ *		  when "DONE" and fifo not emptied.
+ * SMICS_TXW	: TX fifo needs writing: 1 when less than 1/4 full.
+ * SMICS_AFERR	: AXI FIFO error: 1 when fifo read when empty or written
+ *		  when full. Write 1 to clear.
+ * SMICS_EDREQ	: 1 when external DREQ received.
+ * SMICS_PXLDAT	:  Pixel data:	write 1 to enable pixel transfer modes.
+ * SMICS_SETERR	: 1 if there was an error writing to setup regs (e.g.
+ *		  tx was in progress). Write 1 to clear.
+ * SMICS_PVMODE	: Set to 1 to enable pixel valve mode.
+ * SMICS_INTR	: Set to 1 to enable interrupt on RX.
+ * SMICS_INTT	: Set to 1 to enable interrupt on TX.
+ * SMICS_INTD	: Set to 1 to enable interrupt on DONE condition.
+ * SMICS_TEEN	: Tear effect mode enabled: Programmed transfers will wait
+ *		  for a TE trigger before writing.
+ * SMICS_PAD1	: Padding settings for external transfers. For writes: the
+ *		  number of bytes initially written to  the TX fifo that
+ * SMICS_PAD0	: should be ignored. For reads: the number of bytes that will
+ *		  be read before the data, and should be dropped.
+ * SMICS_WRITE	: Transfer direction: 1 = write to external device, 0 = read
+ * SMICS_CLEAR	: Write 1 to clear the FIFOs.
+ * SMICS_START	: Write 1 to start the programmed transfer.
+ * SMICS_ACTIVE	: Reads as 1 when a programmed transfer is underway.
+ * SMICS_DONE	: Reads as 1 when transfer finished. For RX, not set until
+ *		  FIFO emptied.
+ * SMICS_ENABLE	: Set to 1 to enable the SMI peripheral, 0 to disable.
+ */
+
+#define SMICS_RXF	(1 << 31)
+#define SMICS_TXE	(1 << 30)
+#define SMICS_RXD	(1 << 29)
+#define SMICS_TXD	(1 << 28)
+#define SMICS_RXR	(1 << 27)
+#define SMICS_TXW	(1 << 26)
+#define SMICS_AFERR	(1 << 25)
+#define SMICS_EDREQ	(1 << 15)
+#define SMICS_PXLDAT	(1 << 14)
+#define SMICS_SETERR	(1 << 13)
+#define SMICS_PVMODE	(1 << 12)
+#define SMICS_INTR	(1 << 11)
+#define SMICS_INTT	(1 << 10)
+#define SMICS_INTD	(1 << 9)
+#define SMICS_TEEN	(1 << 8)
+#define SMICS_PAD1	(1 << 7)
+#define SMICS_PAD0	(1 << 6)
+#define SMICS_WRITE	(1 << 5)
+#define SMICS_CLEAR	(1 << 4)
+#define SMICS_START	(1 << 3)
+#define SMICS_ACTIVE	(1 << 2)
+#define SMICS_DONE	(1 << 1)
+#define SMICS_ENABLE	(1 << 0)
+
+/* Address register bits: */
+
+#define SMIA_DEVICE_MASK ((1 << 9) | (1 << 8))
+#define SMIA_DEVICE_OFFS (8)
+#define SMIA_ADDR_MASK (0x3f)	/* bits 5 -> 0 */
+#define SMIA_ADDR_OFFS (0)
+
+/* DMA control register bits:
+ * SMIDC_DMAEN	: DMA enable: set 1: DMA requests will be issued.
+ * SMIDC_DMAP	: DMA passthrough: when set to 0, top two data pins are used by
+ *		  SMI as usual. When set to 1, the top two pins are used for
+ *		  external DREQs: pin 16 read request, 17 write.
+ * SMIDC_PANIC*	: Threshold at which DMA will panic during read/write.
+ * SMIDC_REQ*	: Threshold at which DMA will generate a DREQ.
+ */
+
+#define SMIDC_DMAEN		(1 << 28)
+#define SMIDC_DMAP		(1 << 24)
+#define SMIDC_PANICR_MASK	(0x3f << 18)
+#define SMIDC_PANICR_OFFS	(18)
+#define SMIDC_PANICW_MASK	(0x3f << 12)
+#define SMIDC_PANICW_OFFS	(12)
+#define SMIDC_REQR_MASK		(0x3f << 6)
+#define SMIDC_REQR_OFFS		(6)
+#define SMIDC_REQW_MASK		(0x3f)
+#define SMIDC_REQW_OFFS		(0)
+
+/* Device settings register bits: same for all 4 (or 3?) device register sets.
+ * Device read settings:
+ * SMIDSR_RWIDTH	: Read transfer width. 00 = 8bit, 01 = 16bit,
+ *			  10 = 18bit, 11 = 9bit.
+ * SMIDSR_RSETUP	: Read setup time: number of core cycles between chip
+ *			  select/address and read strobe. Min 1, max 64.
+ * SMIDSR_MODE68	: 1 for System 68 mode (i.e. enable + direction pins,
+ *			  rather than OE + WE pin)
+ * SMIDSR_FSETUP	: If set to 1, setup time only applies to first
+ *			  transfer after address change.
+ * SMIDSR_RHOLD		: Number of core cycles between read strobe going
+ *			  inactive and CS/address going inactive. Min 1, max 64
+ * SMIDSR_RPACEALL	: When set to 1, this device's RPACE value will always
+ *			  be used for the next transaction, even if it is not
+ *			  to this device.
+ * SMIDSR_RPACE		: Number of core cycles spent waiting between CS
+ *			  deassert and start of next transfer. Min 1, max 128
+ * SMIDSR_RDREQ		: 1 = use external DMA request on SD16 to pace reads
+ *			  from device. Must also set DMAP in SMICS.
+ * SMIDSR_RSTROBE	: Number of cycles to assert the read strobe.
+ *			  min 1, max 128.
+ */
+#define SMIDSR_RWIDTH_MASK	((1<<31)|(1<<30))
+#define SMIDSR_RWIDTH_OFFS	(30)
+#define SMIDSR_RSETUP_MASK	(0x3f << 24)
+#define SMIDSR_RSETUP_OFFS	(24)
+#define SMIDSR_MODE68		(1 << 23)
+#define SMIDSR_FSETUP		(1 << 22)
+#define SMIDSR_RHOLD_MASK	(0x3f << 16)
+#define SMIDSR_RHOLD_OFFS	(16)
+#define SMIDSR_RPACEALL		(1 << 15)
+#define SMIDSR_RPACE_MASK	(0x7f << 8)
+#define SMIDSR_RPACE_OFFS	(8)
+#define SMIDSR_RDREQ		(1 << 7)
+#define SMIDSR_RSTROBE_MASK	(0x7f)
+#define SMIDSR_RSTROBE_OFFS	(0)
+
+/* Device write settings:
+ * SMIDSW_WWIDTH	: Write transfer width. 00 = 8bit, 01 = 16bit,
+ *			  10= 18bit, 11 = 9bit.
+ * SMIDSW_WSETUP	: Number of cycles between CS assert and write strobe.
+ *			  Min 1, max 64.
+ * SMIDSW_WFORMAT	: Pixel format of input. 0 = 16bit RGB 565,
+ *			  1 = 32bit RGBA 8888
+ * SMIDSW_WSWAP		: 1 = swap pixel data bits. (Use with SMICS_PXLDAT)
+ * SMIDSW_WHOLD		: Time between WE deassert and CS deassert. 1 to 64
+ * SMIDSW_WPACEALL	: 1: this device's WPACE will be used for the next
+ *			  transfer, regardless of that transfer's device.
+ * SMIDSW_WPACE		: Cycles between CS deassert and next CS assert.
+ *			  Min 1, max 128
+ * SMIDSW_WDREQ		: Use external DREQ on pin 17 to pace writes. DMAP must
+ *			  be set in SMICS.
+ * SMIDSW_WSTROBE	: Number of cycles to assert the write strobe.
+ *			  Min 1, max 128
+ */
+#define SMIDSW_WWIDTH_MASK	 ((1<<31)|(1<<30))
+#define SMIDSW_WWIDTH_OFFS	(30)
+#define SMIDSW_WSETUP_MASK	(0x3f << 24)
+#define SMIDSW_WSETUP_OFFS	(24)
+#define SMIDSW_WFORMAT		(1 << 23)
+#define SMIDSW_WSWAP		(1 << 22)
+#define SMIDSW_WHOLD_MASK	(0x3f << 16)
+#define SMIDSW_WHOLD_OFFS	(16)
+#define SMIDSW_WPACEALL		(1 << 15)
+#define SMIDSW_WPACE_MASK	(0x7f << 8)
+#define SMIDSW_WPACE_OFFS	(8)
+#define SMIDSW_WDREQ		(1 << 7)
+#define SMIDSW_WSTROBE_MASK	 (0x7f)
+#define SMIDSW_WSTROBE_OFFS	 (0)
+
+/* Direct transfer control + status register
+ * SMIDCS_WRITE	: Direction of transfer: 1 -> write, 0 -> read
+ * SMIDCS_DONE	: 1 when a transfer has finished. Write 1 to clear.
+ * SMIDCS_START	: Write 1 to start a transfer, if one is not already underway.
+ * SMIDCE_ENABLE: Write 1 to enable SMI in direct mode.
+ */
+
+#define SMIDCS_WRITE		(1 << 3)
+#define SMIDCS_DONE		(1 << 2)
+#define SMIDCS_START		(1 << 1)
+#define SMIDCS_ENABLE		(1 << 0)
+
+/* Direct transfer address register
+ * SMIDA_DEVICE	: Indicates which of the device settings banks should be used.
+ * SMIDA_ADDR	: The value to be asserted on the address pins.
+ */
+
+#define SMIDA_DEVICE_MASK	((1<<9)|(1<<8))
+#define SMIDA_DEVICE_OFFS	(8)
+#define SMIDA_ADDR_MASK		(0x3f)
+#define SMIDA_ADDR_OFFS		(0)
+
+/* FIFO debug register
+ * SMIFD_FLVL	: The high-tide mark of FIFO count during the most recent txfer
+ * SMIFD_FCNT	: The current FIFO count.
+ */
+#define SMIFD_FLVL_MASK		(0x3f << 8)
+#define SMIFD_FLVL_OFFS		(8)
+#define SMIFD_FCNT_MASK		(0x3f)
+#define SMIFD_FCNT_OFFS		(0)
+
+#endif /* BCM2835_SMI_IMPLEMENTATION */
+
+#endif /* BCM2835_SMI_H */